SciPost Submission Page
Higgs decays to two leptons and a photon beyond leading order in the SMEFT
by T. Corbett, T. Rasmussen
This Submission thread is now published as
Submission summary
| Authors (as registered SciPost users): | Tyler Corbett |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202208_00084v1 (pdf) |
| Date accepted: | 2022-09-06 |
| Date submitted: | 2022-08-30 14:01 |
| Submitted by: | Corbett, Tyler |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approaches: | Theoretical, Phenomenological |
Abstract
We present the three-body decay of the Higgs boson into two leptons and a photon to dimension-eight in the Standard Model Effective Field Theory (SMEFT). In order to obtain this result we interfere the full one-loop Standard Model result with the tree-level result in the SMEFT. This is the first calculation of the partial width of the Higgs boson into two leptons and a photon in the SMEFT to incorporate the full one-loop dependence for the Standard Model as well as the full tree level dimension-eight dependence in the SMEFT. We find that this channel can aid in distinguishing strongly interacting and weakly interacting UV completions of the SMEFT under standard assumptions. We also find that this channel presents the opportunity to distinguish different operator Classes within the SMEFT, potentially including contact $H\bar\ell\ell\gamma$ operators which are first generated only at dimension-eight in the SMEFT.
Author comments upon resubmission
We now regulate the collinear divergences by requiring the cosine of the angles between the photon and the leptons to be larger than 0.8. The reasoning for this is described in the new Appendix G. In the work of Han and Wang, arXiv:1704.00790, they define an arbitrary beam axis and from their make cuts on pseudorapidity. This is not Lorentz covariant as demonstrated in the Appendix. We have chosen cos\theta<0.8 as this is a conservative value defined such that the scaling of the leading versus next to leading corrections in the small lepton mass scale as expected, namely m_lep^2/M_H^2.
This new cut has the effect of essentially lowering the tree level partial widths in the SM by nearly an order of magnitude. The impact on the other partial widths is small. Overall this does not affect the qualitative discussion at the end of the paper. It does, however, have a noticeable numerical impact on the results. As they are normalized to the sum of the SM tree and loop contributions, generally the contributions that rescale the SM tree contribution are smaller and the others are larger.
List of changes
We have implemented a cut on the angle between the photon and leptons in order to regulate the collinear divergences. All partial widths have therefore changed. We added an appendix elaborating on our choice of cut.
Published as SciPost Phys. 13, 112 (2022)
Reports on this Submission
Report #1 by Anonymous (Referee 1) on 2022-9-2 (Invited Report)
- Cite as: Anonymous, Report on arXiv:scipost_202208_00084v1, delivered 2022-09-02, doi: 10.21468/SciPost.Report.5626
Report
The authors have updated the results removing the sensitivity to infrared physics, now including an angular separation between photon and lepton. These are important changes, and clearly a better understanding of the results is achieved.
The new appendix (appendix G) describes this implementation of this. Note that the energy cut placed on the photon in this manuscript (in the Higgs rest frame) is also not lorentz invariant. If you wish to make those selections lorentz invariant and both IRC safe, then one could have simply cut on something like ($p_l \cdot p_{\gamma}$) and ($p_{\bar{l}} \cdot p_{\gamma}$). I’m not suggesting this change is made, but it does seem strange (unnecessary) to criticise the work of others for doing something which is not invariant, while doing something similar.
Finally, the authors should indicate whether the results in appendix E now also include the the collinear separation or not. The numerics have not changed since the last submission, so I suspect not.
I would recommend the paper to be published in its current form.